Sekiro: Malevolence - Demon of Hatred (DB)

As mentioned in the Shigekichi video, Frail Blaze Wax (and its other upgrades as well, but Frail lasts the longest for some reason) blocks chip damage and burn buildup from deflecting fire attacks, which means you don't even need the Lotus Umbrella for this fight. Dump all your Emblems into Malcontent, Spiritfalls, or whatever Combat Art you're taking for a spin. Including setup time, this fight has overtaken my Land of Reeds DoH fight as the shortest DoH fight I've got. No Charmless is a bit cheating, but meh.